The invention relates generally to a distributed power generator system, and more particularly to a solar array configuration that utilizes a plurality of voltage boosters distributed throughout the array proximate associated strings of solar modules.
A solar (or photovoltaic) array is a linked collection of solar modules, which are in turn made of multiple interconnected solar cells. The cells convert solar energy into direct current (DC) electricity via the photovoltaic effect. Modules are linked together to form an array. The modules in a solar array are usually first connected in series to obtain the desired voltage, and then the individual strings are connected in parallel to allow the system to produce more current. At some point down the line, after all of the modules are coupled together in a single line, an inverter is utilized to convert the DC power produced by the modules into alternating current (AC).
FIG. 1 depicts a typical configuration of a solar array system 10. Solar array system 10 includes a solar array made up of a plurality of solar modules 12. The solar array system 10 includes a plurality of combiner boxes 14A, 14B, 14C, 14D that couple sets of strings 16 in parallel. Each combiner box typically also includes a set of fuses 17 for each series string of modules. As noted, the parallel connections increase the current on each associated output line 15A, 15B, 15C, 15D. A second stage combiner box 18 may likewise be utilized to further combine the lines into a single DC line 26. In many applications, the DC lines exiting the fused combiner boxes 16, 18 may be hundreds or thousands of meters in length in order to carry the current from the solar modules (often located over many acres) to a terminal point.
Located near the terminal point is an inverter assembly 20, 22 that receives the single DC line 26 and converts DC to AC, providing all necessary safety functions required for interconnection with AC switch gear 24. The inverter assembly 20, 22 includes two stages, a first stage 20 comprising a DC disconnect 28 and a DC-DC converter 30 and a second stage 22 comprising a isolating transformer 32 and an AC disconnect 34. The DC and AC disconnects 28, 34 are implemented as safety features. The first stage 20 utilizes the DC-DC converter 30 to boost the inputted array voltage on line 26 to supply a DC link voltage. The second stage 24 converts the DC link voltage to AC. In this case, the inverter assembly 20, 22 ties directly into existing AC switch gear 24. This is typically completed with a supply side tap located between the utility meter and the utility main. One of the drawbacks of this configuration in a large scale application is the amount of wire (typically copper) required to connect the combiner boxes 14A, 14B, 14C, 14D, 18 with the inverter assembly.